Automatic field start control for code type communication systems



May 2, 1950 J. l. VAUGHN AUTOMATIC F11-:LO START CONTROL FOR CODE TYPE COMMUNICATION SYSTEMS 2 Sheets-Sheet 1 Filed May 26, 1945 May 2, 195o .1. VAUGHN AUTOMATIC FIELD START CONTROL FOR coDE TYPE COMMUNICATION SYSTEMS Filed May 26, 1945 2 sheets-sheet Fl e. 2A. /af

(ttorneg Patented May 2, 1950 AUTOMATIC FIELD START CONTROL FOR CODE TYPE COMMUNICATION SYSTEMS John I. Vaughn, Webster Groves, Mo., assignor to General Railway Signal Company, Rochester,

Application May 26, 1945, ScrialNo. 595,936

8 Claims.

This invention relates to centralized traic control or C. T. C. systems for railroads, and more particularly to the automatic iield start control for code type communication systems employed in connection with such C. 'I'. C. systems.

In the typical code type communication system for centralized traiiic control, to which this invention more particularly relates, code transmitting apparatus at each of the various field stations is employed for transmitting to the control office indications of the position or condition of various devices at the corresponding field location for the information of the operator, such as the position and locked condition of a power operated track switch, the clear or stop indication of signals, and the occupied or unoccupied condition of certain track sections. In the usual organization for systems of this type, when a given field station operates to transmit indications during an operating cycle, a plurality of indications corresponding to the existing position or condition of all of the devices to be indicated, and associated with that field station, are transmitted to the control oflice by what may be termed a scanning operation. Such scanning of the indicating conditions of the changeable devices at a eld station is desirable, because in the normal operation a plurality of changes in the condition of a track switch, signal or associated track circuit often occurs at substantially the same time; and there is a substantial saving in the number of operating cycles required to communicate the proper information to the control oflice, if the indicating conditions or positions of all devices are communicated during the same operating cycle.

In order that these indications under consideration may be transmitted as soon as there is any new information to be communicated to the control office, it is common practice to provide suitable automatic field start means to condition the coding apparatus at a iield station for operation whenever there is a change in the position of a track switch, indications of signals, occupancy of track sections, or the like. When such automatic eld start occurs, in response to the change in the condition of any device to be indicated, there are some circumstances or conditions under which no new information of particular importance or interest to the operator is transmitted during certain of the successive indication cycles resulting from such automatic eld start control. This is more particularly true in connection with the movement of a train into and out of thedetector track section and approach track sections associated with a rack switch.

The primary object or purpose of the present invention is to provide an automatic iield start control for code communication systems used in centralized traiiic control, so as to eliminate certain operating cycles for transmission of indications during which information of little value to the operator would otherwise be transmitted, and thereby reduce the number of indication cycles and obviate any delay in the transmission of controls or indications as between the control oice and the various field stations that might otherwise be caused by such unnecessary indication cycles. i

Generally speaking, and'without attempting to dene the nature and scope of the present invention, it is proposed to provide a special control means for suppressing under certain conditions for a time an automatic iield start that would be caused by a change in some device to be indicated, until a subsequent change in some other device has occurred, in such a manner that the appropriate indications of all changed conditions needed to be known by the operator are transmitted, while indications of no immediate interest or importance are postponed until transmitted during some subsequent operating cycle along with other useful information.

Various other objects, characteristic features, attributes and advantages of the invention are more conveniently considered hereinafter in connection with a detail description of one speciiic embodiment of the invention.

In describing the invention in detail, reference will be made to the accompanying drawings which illustrate in a simpliiied and diagrammatic manner one specic embodiment of the invention, the parts and circuits being shown more with a view of facilitating an explanation and understanding of the invention than for the purpose of illustrating in detail the construction and arrangement of parts preferably employed in practice.

In these drawings, connections to the opposite terminals of a battery or other suitable source of current are indicated by arrows and the symbols and Also, the contact lingers for each of the various relays are shown in the horizontal position when the relay is energized, and in an inclined position when the relay is deenergized; and the contact 1in-gers for each relay are shown either above or below the representation of its coil or winding with connecting dash lines, as is most convenient in illustrating the circuit connections.

In the accompanying drawings, Fig. 1 shows digrammatically and conveniently one form of the invention applied to the transmission of track Vserve to show the conditions under which automatic field starts occur in accordance with this jlinvention for such a train movement.

The present invention is appllblc to of code communication system suitable for centralized traffic control systmsfzalld #also topyari, ous arrangements for proyi g automatic field starts; but `in the interests of simplicity, only one particular embodiment of the irivelatiQlz hasbn illustrated in connection with an automatic field start control of the type shown and described more in detail in prior` patents, such as Judg` eNo.2,13,363December 6, ,1938; Judge, et al.,.No. .ZlQc'ZJ-ii Jlzlplo 1931, and "Nelis, N0- 2,159,922, :May,23,f;19.39

I n this type of automatic eld start control contemplated, the .desired field start -is created -yvhen a Ynormallyener-size.Cl stick relay CH is dev.enersized .by `.momentaryinterrupton of -itsstiok circuit. vThis .change relay CH, when thus deenergized, oroyides the desired conditioning of .the ffieid station coding apparatus Vfor operation lfor ,an indication cycle -by .a closure of a back .Contact in the manner more fully explained-m therprior patents above mentioned, the ',olltiop.q 'lar way inwhich the .operation of the ,change relay CH results in the initiation of. an indica'- circuit readily traced in Fig. l from (als) .through ,-1

a frontV contact vE of a relay LO, energized when the field station in question is operating for an indication'cycle, front contact 'I of a step Yrelay V3, closed at .the point in the stepping opera- 'tion just prior tothe transmission of indications, and a back contact 8 of -a step relay Vfl to provide a temporary `closure of this pick-up circuit, through winding of relay CH, to After restoration of the change relay CH in this mand nenif. a change should occ-ur during the transmission Vof indica-tions, and perhaps after the corresponding indication had VVbeen transmitted, the interruption of the stick circuit for the relay by Chance would establish .another heid siert Condition, since .the pick-up Circuit previously mentionedfor this relay .CH is only .mo- -nieritarily established during the rst part of ing cycle indications of the then existing condi tion of all of the various track relays iATR, ZTR, SATR, the signal repeater relays IRM and iLli/l, and other devices to be indicated but not shown,

by reason of the fact that contacts associated with these relays govern the energization ci indication control circuits shown'diagrammatically operating cycle.. '..lhis .feature is characteristic Y .ofthe prior eld start arrangements such .es disclosed. in the patents above mentioned, and .forms no part .of the improvement e.ons'siii/Lithia .this inv,e.11tion.. Y

When the Y field station .coding apparatus .(shoyvn schematically and enclosed within a .dotted rectangle) is thus conditioned Y,for :opereetion'by energization of .its start circuit by closure of back contact 5 of change relay CH, Ythis .cod- Ving apparatus operates in the usual manner characteristic of systems of this type to transmit at .the appropriate time shrine indication oreret- 1 .so as to determine theicha'racter of the indication code elements, the specific operation in this :respect being dependent upon the particular type .oicodecolmlunication system employed.

.I1 Villustrates `the invention applied to a typical track 'layout comprising a single switch SlT/',Fassrnned to he located at the end oiA a passing siding of 1.a Asingle track railroad, together with signals iRA, TRB, and ILA and ELB of any ,suitable typefcontrolled in accordance with :en cognized practice, for governing train movement `ironfi left to right, andrright to left, respectively', over the track switch Y53W in its normal and reverse positions. The` track `.switch SW is vasfsumed'to be connected to .and operated bythe :usualepower operated switchinachime .'SM; itheoperated vposition of thisswi-tch, -together'witn the indications of the associated signals, Vis Vgoverned .by .the operator "by the transmission of 4suitable switch :and .signal :control codes Vfrom thecontrol oce to the `particular held station in cuestion during an operating .cycle ifor :transu Emission-of contro-ls, in the usual manner .cha-rac- :teristic of centralized Avtrailic .control systems of -the Atype under consideration.

Associated with vthetrack .switch SW is the -usua'l detector track section ET, 'having the usual 1track relay ':2TR. Also, vit is assumed `that 4the occupancy of `.two ,approach Itrack .sections :IAT and SAT adjacent the detector track ysection 2T lor.- lopposite sides thereof 4will also be indicated iin vthe control-cnice. The approach track .secvvtions, such as 'shown in FigA 1 as iiAT and when used -in connection with `approach 'locking control for la power operated switch, generally include a Vplurality vof track sections to provide approach control limits extending one track sectienV inthe rear of an `approach or distanJr signal; ibut-in the interests of simplicity, only one Vapproaclfi `track section IAT fhas been shown for an east-bound train 4rifiovernent toward the switch, and one Vtrack section EAT for -a westbound train movement. Each of these Ytrack sectionsY LAT @AT is 4provided with the usual track relay and SATB. Y

'In the particular arrangement shown, it is assurned that indications of the clear or stop condition `of the respective pairs of signals IRA, IRB and ILA, ILB will be transmitted to the fcontrol ofiice. The automatic `field start for such indications, and the nature of the indication vto be transmitted, are determined by relays IRM K and ILM repeating the .indicating condition of the associated signals IRA,V IRB and iLA, ILB. In the simplified arrangement shown, these sigllals are assumed to be provided with suitable circuit .controllers I to i3, shown converitionallyV `As a typical example of the functions and `mode of operation of the automatic field start means constituting this invention, assume that an east-bound train is to proceed on the main track shown in Fig. 1. For such a train movement, the operator sends out the appropriate controls to position the track switch SW in the normal position and govern the signal ERA to indicate clear. The indications associated with the operation of the switch machine, are assumed to be transmitted in the usual manner, and the circuits for doing this have not been shown. When the signal IRA clears, its repeater relay IRM is deenergized to shift its conta-ct finger I6 from a front contact to a back contact; and during this movement of this contact finger I8, there is a momentary interruption in the normally energized stick circuit for the change relay CH. This circuit as a whole may be traced from through contact nger I5 of relay ILM, contact nger I6 of relay IRM, contact finger I'I of approach track relay 3ATR, contact finger I8 of approach track relay I ATR, contact finger I9 of the detector track storage relay ZTRS, front contact 20 of relay CI-I, winding of this relay, to

Thus, when the signal IRA clears for the train movement under consideration, the change relay CH is deenergized to create a field start and cause transmission of a new signal clear indication to the control oiice.

Considering now the movement of an leastbound train along the main track, it can be seen that this train will enter and leave successively the track sections IAT, 2T and 3AT; and when the changes in the condition of the associated track relays are separated by intervals sufncient for an operating cycle to transmit indications, as will likely happen with trains of substantial length running at relatively low speeds, each change in the energized or deenergized condition of each track relay will be followed by an indication cycle, if the usual arrangement of automatic eld start control is provided as disclosed in the prior patents above mentioned. These different changes for an east-bound train movement are illustrated in the diagrams of Fig. 2A to Fig. 2F; and by reference to these diagrams it can be seen that these changes involved in sequence entrance of the train into approach track section IAT, its entrance to the detector track.`

section 2T, its entrance to the other approach track section 3AT, and leaving in turn track sections IAT, 2T and BAT. In other words, there are in effect six distinctive conditions of track circuit occupancy during this train movement; and if each of these ychanges was followed by an indication cycle, there must be six separate indicating cycles for transmission of this information regarding train movement to the operator in the control ofce.

Certain of these changes in track occupancy, however, are of no particular signicance o! use to the operator, because such change in train location does not call for or permit a new or different manipulation on the part of the operator, and the progress of the trains into and out of certain track circuits does not afford essential information.

Considering these conditions more in detail, it is desirable to transmit an indication for the information of the operator when the east-bound train under consideration i-lrst enters the approach track section IAT, because this indicates that the train has arrived Within the approach locking limits, and no immediate change can, or should be, made in the route set up.

Also, it is desirable to transmit an indication to the control office when the train enters the detector track section 2T, because this advises the operator when it would be permissible to send out controls to change the position of the switch and clear a signal for some other train movement, such as for a west-bound train to come off of the passing siding in connection with a meet.

However, when the head end of the eastbound train' under consideration has progressed to the point where it enters the next approach track section SAT, as indicated in Fig. 2C, it is considered that an indication of this change in the track occupancy need not be transmitted for the time being, because the fact that the train has progressed to this point does not permit, or call for, any additional manipulation on the part of the operator. Accordingly, and in accordance with this invention, it is proposed to suppress or postpone the automatic field start occurring under such conditions.

Similarly, when the rear end of the eastbound train under consideration has cleared the approach track section IAT, as indicated in Fig. 2D, there is no need for transmitting an indication of this condition to the control office, because such information is of no particular significance or interest to the operator.

When the rear end of the east-bound train under consideration has cleared the detector track section 2T, however, it is desirable to transmit an indication of this change to the control office, because this represents a condition where the switch should start its operation and the signal clear, if such control had been exercised and also the condition where such control may be exercised. In other words, the fact that the detector track section 2T has become unoccupied is a matter of significance to the operator, and the automatic field start for such an indication should be provided. The indications showing the then existing unoccupied condition of the approach track section IAT and the occupied condition of the other approach track section SATR will be transmitted on the same indication cycle'along with the indication of movement of the train out of the detector track section 2T; and hence the desired information of. such occupancy is received in the control oiiice at the appropriate time, even though as above pointed out, such indications were not transmitted when the track section IAT was rst vacated and the track section SAT was rst entered.

When the train in question leaves the approach track section SAT, as indicated in Fig. 2F, it is of course desirable to transmit an indicationv of this fact to the control ofce, since this represents the progress of the train which is of material interest to the operator.

In the diagrams of Fig. 2A to 2F, indicating lamps IATK, ZTK and ATK for the respective track sections IAT, 2T and 3AT have been illustrated, with a diagrammatic representation of when these indicating lamps are extinguished or lighted, in order to represent the indications for the dilerent positions of the train as they appear before the operator on the usual miniature track diagram on his control machine. It should be understood, of course, that the indicating lamps illustrated for explanatory purposes in these Figs. 2A-2F are in the control oice, and are not associated with the track over which the train moves.

Y l With thisV explanation of the desired objectives forlan automatic field start control in connection with a typical eastbound tainmovement, 'consideration may -now be given to the specific ar- /ZTR is released, and `vin due time the signal IRA assumes its stop position and cnergizes its re-v fle/alter relay IRM, thereby `establishing a pick-up circuit for the 'track storage relay 2'fI`RS, which may he readily traced from (-l-Lrthrougli front Ycor'lta'cts' 23 'and 24 of relays ILM and IRM, back contact or detector track relay 2TR, and winding of relay ZTRS, to

AThe energization of the track storage relay TRS shifts its Contact linger I9 from the back contact position to its front contact position, and momentarily interrupts the stick circuit for the ychange relay VCI-I to provide the desired field start;

'The @neral-muon of this track storage relay ETRS is made dependent upon the energized c'ondition oi the signal repeating relays IRM and ILM, so that ii there is any Substantial delay in a signal assuming its stopposition upon entrance of va train into the detector track section, as in the case of a semaphore signal, the held start caused by the entrance 'of the train into'this detector track section is held up until the signal indicates stop, thereby permitting the indication or" the signal 'at stop to be transmitted on the 'saine ope'latingrciycie rwith the indication of cocu'- paney of the ldetector track section.

It may be ekplained at this point that the track Vstorage relay TES is provided and controlled the manner and for the purpose 'explained mere in detail in the patent to De Long, et al., No. 1,852,492, April 5, 1932'. Briey stated, this track storage relay is' employed to assure that an indication of the occupancy 'of the detector track section will be transmitted to the control `oice even though this track section may be occupied for a short time by a 'fast moving short train, and the condition of occupancy lnay change before the associated field station transmits its indications. maintained energized by a 'stick circuit through its front contact 21 and aback contact 28 kof the relay 'CI-I, until the relay CH i's restored upon transmission of indications from the corresponding 'nele station. An auxiliary stick circuit lnciuding 'a front contact 2e of a slow-release relay SA, energized during the transmission of an indication cycle, is provided to maintain theV relay ETRS energized during the indication cycle after restoration of the relay CH, so that an indication of occupancy will be transmitted, even though V'in the ineantirne` the train has left the detector 'track section and opened the pickaup circuit for the relay 2TRS. This track storage feature forns no 'part 'of the particular improvement constituting this invention, and is shown because terzing` this invention, the energization of the track 'storage relay 2TRS closes a front contact to provide a shunt including wirel around the contact Vfingers I 8 and I'I of the track relays IATR andv SATB for the two approach track sections IAT and 3AT. Consequently, while the relay ZTR is maintained deener'gized by the presence of a train in the detector track section 2T, the entrance of this train into the approach track section SAT, as indicated in Fig. 2C, or the movement of this train out of the other approach track section IAT, as indicated in Fig. 2D, does Anot cause a field start, since the contacts I8 and I1 'of the relays IATR and 3ATR are shunted, and do not change the continuity of the stick circuit for the change relay CH upon operation of these approach track relays.

When the track storage relay ZTRS is released hy the movement of the train out of the detector track section 2T, as indicated in Fig. 2E, or after the transmission of Yan occupied indication, as the case may be, the movement of the contact iinger I9 of this relay IZTRSinterrupts the stick circuit for the change relay CH to create a field start; and indications of theV then existing condition of the approach track sections IAT and 3AT are transmitted on the same operating cycle.

Thus, the indicating lamps IATK for the approach track section IAT, and ZTK for the de'- tectortrack section 2T, Which are lighted on the control panel in the control cnice With thel train in the Vpositions indicated in Figs. 2B, 2C `and 2D, are extinguished, and at the'same time the indicating lamp SATK for the other approach track section EAT is lighted, much the same as if the train Vhad moved all at once inY one stepfrom "the position shown in Fig. 2B to the position eli) It Will be l'loted that the relay 2TRS iS f shown in Fig. 2E. 4

The release of the track storage relay 2TRS, and the opening of its front contact 0 also breaks the shunt around the contact linger I'I of the track relay SATZ-t, so that Whenthe train leaves the track section -3-AT, the operation of this con#- tact finger I1 of this relay 3ATR. is; eifectivel to interrupt thestick circuit for the change relay CH and cause ,a field start. v Y

A similar sequence of operation is involved for a train movement in the opPQsite direction; and it can be seen without detail explanation that the entrance of such a Westf-bound train into the second approach track `section IAT and its movement out of the rsttrack section -3AI` are suppressed or postponed until this train has vacated the detector track section 52T. gI'f the eastbound train previously mentioned should enter the passing siding, the sequence of operation is the same as that described, except therel is no indication of the'movement; of such train into and rout of the other approach'track section 3AT. In the case of aHwest-'bound trail-n coming oil? of the siding on the Vmain track, the indication of the entrance ofV this train into the approach track section IAT is suppressed or postponed in the 'same` manner described, until this train has left the detector track section 2T.

From the foregoing it can'be seen that a relatively simple arrangementV of circuits in accordance with this invention serves to eliminate the transmission of certain indications in connection with train movement over successive track seotions which are not of particular significance for Y the information of the operator, so as to mate- V7,5 ciated that the same principles 4and similar circuit arrangements may be employed to suppress or delay unnecessary eld starts in connection with other kinds of train movements over other arrangements of track sections; and the invention-is in no way limited to the particular arrangement of track sections shown and described, which are merely typical of conditions encountered in practice. Also, the same principles and mode of operation. characterizing this invention may be applied to other types of means for creating fleld starts, with such adaptations or variations in the circuit connections as may be required to carry out the function or" suppressing or delaying certain eld starts while a predetermined condition exists, such as the occupancy of the detector track section in the particular arrangement disclosed.

The particular embodiment of the invention shown and described is merely typical or illustrative of the nature and character of the invention; and I desire to have it understood that various adaptations, modications, and additions may be made to the particular organization of parts and circuits illustrated, without departing from the invention.

What I claim is:

1. In a code type communication system for centralized traic control on railroads, code transmitting apparatus at a eld station acting when set in operation by a field start to transmit indications during an operating cycle to a distant control o'ice, two adjacent track sections associated with said eld station to have their condition of occupancy indicated in the control oiice, and means responsive to the entrance of a train into each of said track sections as the train progresses for creating a field start to condition said code sending apparatus for operation, said means also creating a eld start when such train leaves the second track section it enters for a given direction of traiic but not when it leaves the other track section.

2. In a code type communication system for centralized tra'ic control on railroads, the combination with a detector track section for a track switch and an adjacent approach track section each having a track relay, neld station coding apparatus acting when set into operation to transmit during an operating cycle indications to a distant control oiiice or" the occupied or unoccupied condition of both of said track sections, and automatic field start means governed by said track relays for conditioning said coding apparatus for operation when a train enters said approach track section and said detector track section in turn, and also when such train leaves the detector track section but not when it leaves the approach track section to enter said detector track section.

3. In a code communication system of the character described, the combination with a detector track section for a track switch and two approach track sections one on each side of said detector track section, each of said track sections having a track relay, eld station coding apparatus acting when set into operation to transmit to a distant control office indications of the condition of occupancy of all of said track sections, and field start means governed by said track relays for conditioning said coding apparatus for operation when a train enters one of said approach track sections and said detector track section in turn, and also when such train leaves said detector track section, but not when such train leaves the approach track section rst entered or enters the other approach track section.

4. In a code communication system for centralized traino control, a detector track section for a track switch and an adjacent approach track section each having a track relay, field station coding apparatus associated with said track sections acting when set into operation to transmit indications to a distant control oice of the condition of occupancy of both trackvsections, circuit means responsive to the energization or deenergization of the track relay for said approach track section for conditioning said coding apparatus for operation, and circuit means responsive to the energization or deenergization of the detector track relay for conditioning said coding apparatus for operation and also acting while said detector track relay is deenergized to render the track relay for said approach track section ineffective to govern the operation of said coding apparatus.

5. In a system of the character described, the combination with a plurality of adjacent track sections each having a track relay, coding apparatus operable to transmit indications of the condition of occupancy of said track sections, a, normally energized circuit acting when broken t0 condition said coding apparatus for operation, contact means associated with each of said track relays for temporarily interrupting said circuit when that track relay is energized or deenergized, and means effective while said track relay for one of said track sections is deenergized for rendering the contact means associated with the other track section ineffective to control said circuit.

6. In a code type communication system for centralized traffic control on railroads, a detector track section for a track switch and two other adjacent approach track sections one on each side of said detector track section, each of said track sections having a track relay, field station coding apparatus including a eld start circuit and conditioned for operation by such circuit to transmit indications to a distant control ofce of the condition of occupancy of all of said track sections, contact means associated with each of said track relays normally effective to govern said start circuit when that track relay is energized or deenergized, and means effective while the track relay for said detector track section is deenergized for rendering said contact means associated with the other two track sections ineffective to govern said start circuit.

7. In a code communication system of the character described, a detector track section and an adjacent approach track section each having a track relay, coding apparatus operable to transmit indications to a distant control office of the condition oi occupancy of both of said track sections during an operating cycle, a normally energized change stick relay acting when deenergized to condition said coding apparatus for operation, a stick circuit for said change relay, contact means associated with each of said track relays and normally effective to interrupt said stick circuit upon energization or deenergization of that track relay, and means elective while the track relay for said detector track section is deenergized for providing a shunt around said contact means associated with said adjacent track section.

8. In a code communication system for transmitting indications from the eld stations to a distant control office, a detector track section for 

